해수 배터리 기술 시장 : 동향 및 전망(2027-2047년)

Seawater batteries use natural seawater as the electrolyte and sodium source. The rechargeable version, first demonstrated in 2015, separates a sealed non-aqueous negative electrode compartment from flowing seawater using a NASICON ceramic that conducts sodium ions while remaining stable in water. Sodium is drawn from the seawater on charge and returned on discharge, with oxygen reduction and evolution occurring at an open positive electrode.

The technology has two structural advantages. The active cathode material is supplied by the ocean at zero cost, removing the largest line item in a conventional cell. And a water-immersed cell has no thermal runaway pathway, which matters in applications where fire risk drives siting, insurance and permitting decisions. The open cathode also permits desalination, carbon mineralisation and hydrogen or chlor-alkali co-production, though these have been demonstrated separately rather than simultaneously.

Three constraints are structural and permanent. Deployment is limited to coastal, offshore or seawater-supplied sites. Round-trip efficiency is capped at 60–80% by the voltage gap inherent to oxygen electrochemistry. Seawater intake, filtration and anti-fouling impose a parasitic load and a cost floor with limited learning-curve potential. Cell energy density of 20–75 Wh/kg constrains footprint but does not disqualify the technology from stationary duty.

The technology sits at TRL 4–6. Cycle life has been demonstrated to 100–200 cycles in most published work, against a commercial threshold near 4,000, and no multi-year field data in real seawater exists. The comparison set has moved: lithium-ion reached USD 70/kWh at pack level for stationary storage in 2025, sodium-ion operates at 85–92% efficiency with signed multi-gigawatt-hour supply agreements, and iron-air targets installed costs below USD 20/kWh for 100-hour duration. Two industrial problems gate commercialisation. Large-format NASICON must be manufactured at acceptable yield and cost, and it has no equipment path from the battery industry. Durability must be demonstrated over years in real seawater, which cannot be accelerated in a laboratory. Neither is a scientific obstacle; both require sustained engineering investment.

The addressable market is correspondingly narrow. Marine navigation aids are commercially available. Island and coastal microgrids, where the incumbent is diesel and fresh water has local value, follow. Desalination-coupled plants, coastal data centres and offshore wind installations open later, subject to certification and durability evidence. The supplier base is concentrated in Korea, with one dedicated cell developer, one qualified ceramic supplier and one commercial channel partner.

Parameter / Definition used in this report

• Seawater battery (SWB)
  • A rechargeable electrochemical cell in which natural seawater serves as the catholyte and as the sodium reservoir, separated from a sealed negative-electrode compartment by a sodium-selective solid electrolyte
• Excluded from scope
  • Seawater-activated reserve primary batteries (Mg-AgCl, Al-AgCl); saltwater-electrolyte batteries using manufactured brine, including the former Aquion chemistry; sodium-ion batteries, which are treated as a benchmark and adjacency rather than as the subject
• Baseline year
  • 2026
• Forecast window
  • 2027–2047, reported at 2027, 2030, 2035, 2040 and 2047
• Currency
  • Constant 2026 US dollars unless stated otherwise
• Capacity convention
  • GWh of energy capacity installed per year (flow) and GWh cumulative installed base (stock), reported separately
• Market value convention
  • System-level revenue at the point of sale to the asset owner, excluding EPC and grid connection
• TRL scale
  • EU and NASA nine-point scale

Seawater Battery Technology 2027–2047: Market, Trends and Outlook assesses the rechargeable sodium–seawater battery as a commercial technology. It distinguishes it from seawater-activated primary batteries and from saltwater-electrolyte batteries using manufactured brine, which are frequently aggregated with it in published market data and which account for most of the discrepancy between market valuations for this category. Contents include:

• Lithium-ion pricing and characteristics as comparison baseline
• Post-lithium requirements and entry gates for stationary storage
• Sodium-based battery families; sodium-ion as both supply chain and competitor
• Seawater battery overview, properties, comparison with sodium-ion
• Commercial prospects; environmental and safety assessment; global R&D trends
• Seawater battery technology
  • Half-open cell architecture and implications for degradation
  • Development history: reserve primaries, metal-air primaries, rechargeable systems
  • Advantages and disadvantages, separated into structural and contingent
  • Electrochemical characteristics and thermodynamics
• Seawater battery materials
  • Positive electrode: reaction mechanism, catalyst benchmark, synthesis routes, trends
  • Negative electrode: sodium metal, hard carbon, alloying and conversion materials, anode-free and semi-liquid designs
  • Electrolyte and separator: NASICON against competing sodium conductors; sintering and thin-film routes
  • System and cell design; format development; degradation mechanisms; component maturity
• Standards, certification and safety qualification
  • Certification gates by target application
  • IEC, UL, NFPA, IMO, DNV, IALA, GB/T and EU Battery Regulation requirements
  • Marine discharge consent
• Manufacturing readiness and process technology
  • Manufacturing readiness by component
  • Process assessment and equipment compatibility
• Technical improvements and challenges
  • Challenges ranked by commercial constraint
• Competitive benchmarking
  • Long-duration storage benchmark across seven technologies
  • Iron-air comparison and charging-price sensitivity
• Market and applications
  • Application roadmap and sequencing
  • ESS: solar and wind, offshore and coastal, island and remote grids
  • Marine vessels, small equipment, auxiliary power, ports
  • Hydrogen and chemical co-production
  • Data-center and AI-load applications
  • Environmental footprint, marine discharge and life-cycle assessment
• Global market for seawater batteries
  • Serviceable market by segment
  • Deployment, market value and price path to 2047 under three scenarios
  • Ecosystem structure
  • Cost structure and levelised cost of storage by duration
  • Patent landscape and IP concentration
  • Sensitivities and risk register
• Company profiles
  • Classification of profiled companies by category
  • Profiles across developers, materials suppliers and adjacent technologies including AquaBattery, 4TOONE Corporation, PolyPlus Battery Company, Shenzhen Sea Energy and more......

Table of Contents

1 EXECUTIVE SUMMARY

• 1.1 Lithium-ion battery technology
  • 1.1.1 Pricing
  • 1.1.2 Characteristics
• 1.2 Post-lithium technologies
  • 1.2.1 Requirements
  • 1.2.2 Sodium-based batteries
    • 1.2.2.1 Why sodium-ion matters for seawater batteries
• 1.3 Seawater batteries
  • 1.3.1 Overview
  • 1.3.2 Properties
  • 1.3.3 Comparison with SIB
  • 1.3.4 Seawater batteries commercial prospects
  • 1.3.5 Environmental and safety case for seawater batteries
  • 1.3.6 Global R&D trends
• 1.4 Summary of technology and market
• 1.5 Commercialisation
• 1.6 Supply chain implications
• 1.7 Regulation, trade and transport constraints
• 1.8 Scope, method and definitions

2 SEAWATER BATTERY TECHNOLOGY

• 2.1 Overview
• 2.2 Advantages and disadvantages of seawater batteries
• 2.3 Electrochemical characteristics

3 SEAWATER BATTERY MATERIALS

• 3.1 Positive electrode, seawater side
  • 3.1.1 Reaction mechanism
  • 3.1.2 Materials
  • 3.1.3 Synthesis methods
  • 3.1.4 Technology trends
• 3.2 Negative electrode, sealed side (conventionally the anode)
  • 3.2.1 Reaction mechanism
  • 3.2.2 Materials and anode-free architectures
  • 3.2.3 Synthesis methods
  • 3.2.4 Technology trends
• 3.3 Electrolyte and separator
  • 3.3.1 Properties
  • 3.3.2 Materials
  • 3.3.3 Synthesis methods
  • 3.3.4 Technology trends
• 3.4 System and cell design
  • 3.4.1 Design lessons from metal-air and flow-battery architectures
  • 3.4.2 Degradation and failure modes
  • 3.4.3 Component maturity and the critical path

4 STANDARDS, CERTIFICATION AND SAFETY QUALIFICATION

5 MANUFACTURING READINESS AND PROCESS TECHNOLOGY

6 TECHNICAL IMPROVEMENTS AND CHALLENGES

7 COMPETITIVE BENCHMARKING

• 7.1 The iron-air problem

8 MARKET AND APPLICATIONS

• 8.1 Application areas and sequencing
• 8.2 Energy and Storage Systems (ESS)
  • 8.2.1 Deployment status
  • 8.2.2 Solar and Wind
  • 8.2.3 Offshore and Coastal
  • 8.2.4 Island and Remote Coastal Grids
• 8.3 Marine Vessels and Infrastructure
  • 8.3.1 Small marine equipment
  • 8.3.2 Auxiliary power
  • 8.3.3 Port and offshore power supply
• 8.4 Hydrogen Production
  • 8.4.1 Water electrolysis and the chloride problem
  • 8.4.2 Hydrogen and chemical co-production
• 8.5 Data-center and AI-load power applications
• 8.6 Environmental footprint, marine discharge and life-cycle assessment

9 GLOBAL MARKET FOR SEAWATER BATTERIES

• 9.1 Serviceable market
• 9.2 Deployment and market value scenarios
  • 9.2.1 Scenario design
  • 9.2.2 Deployment outlook
• 9.3 Market value
• 9.4 Market outlook by application
• 9.5 Ecosystem structure
• 9.6 Cost structure and levelised cost of storage
  • 9.6.1 System cost structure and its evolution
  • 9.6.2 Levelised cost of storage
• 9.7 Patent landscape and IP concentration
• 9.8 Scenario sensitivities and risk register
  • 9.8.1 Sensitivity analysis
  • 9.8.2 Risk register

10 COMPANY PROFILES (14 company profiles)

11 APPENDICES

• 11.1 Appendix A. Methodology and data sources
• 11.2 Appendix B. Glossary and acronyms
• 11.3 Appendix C. Readiness level definitions

12 REFERENCES